Nailing device

ABSTRACT

A nailing device having coaxial connected cylinders which are resiliently supported for movement towards an object to be nailed by operation of one cylinder and the second cylinder being, operatively connected to a hammer for driving nails and including means for feeding nails beneath said hammar and means for automatically operating the nailing device when an object is positioned for being nailed.

United States Patent 1191 Charlez 1 Nov. 12, 1974 NAILING DEVICE Rune Kjell Evald Charlez, Tradlyckevagen 84, 432 00 Varberg, Sweden Filed: Aug. 1, 1972 Appl! 'No.: 276,910

Inventor:

us. c1 227/7, 227/124. 227/130. 227/153 1m. (:1 B271 7/02 Field of Search; 227/5, 6, 7, 124, 152, 227/153 References Cited UNITED STATES PATENTS 3,474,947 10/1969 Readyhough I. ,1 227/153 X Smith 227/153 Leach .1 227/124 Primary Examiner-Granville Y. Custer, Jr.

[57] ABSTRACT A nailing device having coaxial connected cylinders which are resiliently supported for movement towards an object to be nailed by operation of one cylinder and the second cylinder being. operatively connected to a hammer for driving nails and including means for feeding nails beneath said hammar and means for automatically operating the nailing device when an object is positioned for being nailed.

4 Claims, 4 Drawing Figures 9 2 4 39 94 do so a 36 3 M 7 $59 as 5, 6 1 I PATENTEDHUV 12 m4 SHEET 10F 3 FIG. 2

mull I FIG; 3

NAILING DEVICE The present invention relatesto a power nailing device.

It is a principal object of the invention to provide a nailing device of the kind mentioned above which is of simple design at the same time as it is reliable in use and by means of which one can obtain a satisfactory nailing result, i.e., nailheads sticking up above the surface of the object to be nailed are avoided, and the same goes for nailheads too deeply buried below said surface.

In the following an embodiment of the invention will be described with reference to the accompanying drawings in which FIG. 1 is a side elevational view of the upper part of the nailing device,

FIG. 2 is a partly broken away side elevational view of the lower part of the same nailing device,

FIG. 3 is a side elevational view partly in cross section perpendicular to the view of FIG. 2 and illustrating the lower end portion of the nailing device, and

FIG. 4 schematically illustrates said nailing device with the equipment belonging thereto for its operation.

The nailing device illustrated in the drawings and in.

its entirety indicated by the reference numeral 1 can suitably be suspended in a frame 2 together with a number of additional nailing devices. The nailing device illustrated in the drawings comprises for one part an upper and for another part a lower hydraulic cylinder 3 and 4 respectively, the end wall portions of which 5 and 6 respectively are rigidly connected with each other. The upper wall portion 7 of the hydraulic cylinder 3 has pistonrod 8 extending therethrough and which rod at its free end is connected with a journalling means 9. The journalling means9 is suspended by a pivot pin 10 which in its turn is suspended by the upper part 11 of a housing 12 of tubular shape in which housing an additional tube 13 is telescopically displaceable and the lower end of said tube 13 via a bracket 14 is connected with the lower wall piece 15 of the hydraulic cylinder 4. A tension spring 36 is enclosed in the housing 12 and tube 13 which spring tends to keep the piston rod 8 in its retracted condition in the hydraulic cylinder 3, i.e., in the position illustrated in FIG. 1. The upper end of a housing 16 of tubular shape is connected with the lower wall piece 15 of the hydraulic cylinder 4 which housing in its lower part encloses an insert 17 in which a central bore 18 is provided and a driver 19 being displaceably journalled therein which driver suitably can be the piston rod of the hydraulic cylinder 4. A sliding bearing for the driver 19 which is press fitted in the insert 17, is indicated at 20. A nail supplying channel 21 opens in the central bore 18 through which channel nails are fed down into the central bore 18 from a magazine not illustrated in the drawings via a preferably flexible conveyor hose 22 when the device is in operation. The insert 17 has a lowerend portion the thickness of which is smaller than the inner diameter of the tube 16. In the space between the inner wall of the tube 16 and said lower end portion of the insert a pressure spring 23 is inserted which with its upper end rests against a shoulder 24 provided at the changeover point between the thick and the thin portion of the insert and at its lower end rests against the upper terminal edge of a ring 25 surrounding the lower end portion of the insert which ring with its lower edge portion by the pressure force of the spring 23 is pressed against two diametrically opposed jaws 27 pivotable each one around its pivot pin 26. In the lower end portion of the insert 17 a sliding sleeve 28 is inserted, the inner bore 29 of which forms a prolongation of the central bore 18. The sliding sleeve 28 has a comparatively thick wall and is provided with longitudinally extending grooves in its sides in which the jaws 27 are pivotably mounted. In the position illustrated in FIG. 2 the lower end portions of the jaws 27 are contacting each other by the bias of the spring 23. When a nail is fed down in the central bore 18 it is by means of the driver 19 which serves the purpose of a. hammer, hammered down whereby the low portions of the jaws 27 are caused to separate against bias of the spring 23, so that also the nail head can pass by said jaws. One side of the lower end portion of the tube 16 has a holder 30 which in its turn supports a verticallydownwardly projecting guide pin 31 which is in a displaceable manner guided in a bushing 32 which is held in a support. 33 which in its turn is adjustably attached to the frame 2 of the machine by means of a bolt 34.

Function of the elements 30 34 is as follows:

The pin is preferably threaded in the holder and vertically slideably guided in the bushing for vertical movement of the cylinders. The support 33 is adjustably attached to the frame 2 of the machine by means of the bolt 34. When the bolt is loosened, said support 33 can be moved in its longitudinal direction, while the element lying between said support and the frame 2 can be adjusted in a direction transverse to the support 33. During this adjustment the support and the last mentioned element can be held together by means of the bolt. When the bolt is tightened the bushing 32 and thus the cylinders are held steadily in a desired position counted in a horizontal plane.

In FIG. 4 the hydraulic cylinders 3 and 4 are schematically illustrated. The cylinders are in between them separated by a wall, which is made up of the wall pieces indicated at 5 and 6 in FIG. 1. The piston displaceable in the hydraulic cylinder 3 is indicated at 35 and its piston rod is as in FIG. 1 indicated at 8. To simplify matters the spring which tends to push the piston rod 8 into the hydraulic cylinder 3 is inserted in said cylinder and is indicated at 36 there. The piston displaceable in the hydraulic cylinder 4 is indicated at .37 and its piston rod is indicated at 38. At the lower end of the piston driver 38 the rod 19 serving the purpose of a hammer is attached. On hydraulic cylinder 3 there is a dog 38 which is arranged to be able to operate a microswitch 40 attached to the frame 2 at a suitable height. A second mirocswitch 41.is mounted in the lower part of the frame 2 in such a position that it is activated at the contact with an object intended to be nailed which in the present case is made up of a pallet 42, when it has occupied a position suitable for being nailed. A hydraulic pump 43 is via a tube 44, an oil. filter 45, a tube 46, a check valve 47 and a tube 48 connected with a pressure vessel 49. A return flow tube 50 is connected to the tube 46, an overpressure valve 51 being fitted in said return circuit and suitably chosen for a working pressure of 200 atmoshere gauge. A feeding tube 52 is connected with the pressure circuit 48 which feeding tube opens at the entrance side of a hydraulic valve 53 which is operated by two coils 54 and 55. The hydraulic valve 53 is provided with two outlets, one of which via a tube 56, in which a pressure reducing valve 57 is fitted, is in communication with the chamber below the piston 35 displaceable in the upper hydraulic cylinder 3, the other one via a tube 58 being in communication with the chamber above the piston 37 displaceable in the hydraulic cylinder 4. When the coil 54 is subjected to a push, the tubes 52 and 58 are in communication with each other, while the communication between the tubes 52 and 58 is interrupted. An adjustable pressure gauge is connected with the circuit 56, the working pressure of said gauge suitably being in the range atmospheric gauge. The guage 59 is via an electric circuit 60 in communication with the coil 54, by which arrangement the coil'54 is subjected to a pull, when the gauge 59 has reached its working pressure. In a correspoding manner an additional pressure gauge 61 is connected with the tube 59, the working pressure of said gauge suitably being in the range 100 200 atmospheric gauge. Via an electric circuit 72 the pressure gauge 61 is in communication with the coil 62 of an additional hydraulic valve 65 with two stable positions, the other coil 63 of which together with the coil 55 of the hydraulic valve 53 is in communication with the switch 41 via an electric circuit 64. The solenoid valve 65 exhibits two inlets, the circuits 56 and 58 being connected with each one of said inlets each one via its branch 66 and 67 respectively. A return flow tube 68 is connected with the outlet side of the hydraulic valve 65 and debouches in a tank 69 for hydraulic fluid. In one of the two stable positions of the hydraulic valve 65 the communication between the branches 66, 67 and the return flow circuit 68 is interrupted, i.e., the coil 63 is subjected to pull, and in the other one of said two stable positions the communication between the branches 66, 67 and the return flow circuit 68 is open, i.e. when the coil 62 is subjected to a pull. As is evident from I of the hydraulic solenoid valve 65.

The functioning of the valve is evident from the following:

When the object intended to be nailed, in the present case a loading pallet, reaches the position illustrated in FIG. 4, i.e., contacts the switch 41, said switch closes the electric circuit to the coils 55 and 63 which means that the hydraulic valve 53 occupies the position, in

which the communication between the tube 52 and the tube 56 is open, i.e., pressure fluid is streaming into the hydraulic cylinder 3, at the same time as the hydraulic valve 65 takes the position, in which the communication between the branches 66, 67 and the tube 68 is interrupted. When the pressure in the tube 56 and the hydraulic cylinder 3 has reached the working pressure of the pressure gauge 59, i.e., when the hydraulic cylinders 3 and 4 have displaced themselves downwards towards the pallet 42 and the lower end portion is contacting said pallet with the desired pressure, then the pressure gauge 59 closes the electric circuit to the coil 54 which means that the communication between the tubes 52 and 58 is opened while the communication between the tubes 52 and 56 is interrupted, i.e., the presthe spring 36. Thereby the piston 37 is pressed down in the working cylinder 4 until the working pressure has been reached in the pressure gauge 61, i.e., when a nail via the feeding conduit 22 has been fed down and rammed into the loading pallet with the desired force. When the pressure gauge 61 has reached its working pressure, it closes the circuit to the coil 62 which pulls the valve to the position into which the communication between the branches 66, 67 and the tube 68 is open. The piston 37 is from the underside subjected to pressurized air, the air pressure suitably permanently being adjusted at approximately 7 atmospheric gauge. Thereby the pistons 35 and 37 are now returned to the starting position illustrated in FIG. 4, the piston 37 by actuation of air pressure from below and the piston 35 by the bias of the spring 36. If by any reason the switch 41 is actuated without any object intended to be nailed has been introduced below the nailing unit and because thereof control pulses reach the coils and 63, whereby the nailing unit is activated, the dog 39 will strike against the switch 40 which via the electric circuit 71 gives a controlling pulse to the coil 62 which like the coils 55 and 63 is pulse controlled, and opens the communication between the branches 66, 67 and the tube 68, whereby the nailing unit returns to its rest position. The coil 54 is suitably made with a spring operated return which means that the valve 53 after each control pulse to the coil 55 returns to the position in which the communication between the tubes 52 and 56 is open. A number of nailing units can suitably be placed at the side of each other, the hydraulic cylinders 3 thereby being coupled in parallel arrangement as well as the hydraulic cylinders 4. This means that one obtains a very uniform nailing result irrespective of considerable variations in the thickness being exhibited by the object intended to be nailed or this not being the case. When a nail is hammered down through the sleeve 28 the jaws 27 are caused to separate against bias of the force from the pressure spring 23 and the ring 25 and immediately after the nail has emerged, they are again pivoted back into the position illustrated in FIG. 2.

The invention is not limited to the embodiments described above and illustrated in the drawings by way of example only, but can be varied as to its details within the scope of the following claims. It is thus within the scope of the invention that instead of hydraulic fluid by way of example air can be used as pressure medium.

What I claim is:

1. A nailing device comprising a stationary holder, a driver, driving means comprising a power unit made up by a first and a second hydraulic cylinder mechanically connected end to end and positioned coaxially to each other with their piston rods extending in opposite directions, means resiliently pressing the piston rod of said first cylinder inwardly of said first cylinder, said second cylinder having its piston rod being positioned for engaging said driver, a nail guide element supported by said second cylinder which guide element will contact the object to be nailed by extension of the piston rod ofsaid first hydraulic cylinder, means for supplying hydraulic pressure medium to said first cylinder for extending its piston rod and-pushing said nail guide element against the object to be nailed, control means for causing pressure medium to be supplied to said second cylinder whose piston rod then acts upon the driver only after the nail guide element has contacted the object to be nailed, and control means for preventing said hydraulic pressure medium for leaving said first cylinder during the working movement of said second cylinder. W t, o is V ZIAnaiIing deViCe according to claim 1 including a spring between said holder and said first cylinder, the bias of which continously strives to retract the piston rod of said first cylinder.

3. A nailing device according to claim 1, wherein said interconnected portions of said hydraulic cylinders consists of one end wall of each of said cylinders.

4. A nailing device according to claim 1, comprising a control valve in said fluid pressure supply means of said hydraulic cylinders, said control valve being adapted to conduct pressure medium alternatively to one of the other of said hydraulic cylinders, means for exhausting pressure medium from said cylinders, a cut off valve in said means for exhausting adapted to keep said means for exhausting open :in one position and 7 closed in another position, a pressure dog in said presachieved. 

1. A nailing device comprising a stationary holder, a driver, driving means comprising a power unit made up by a first and a second hydraulic cylinder mechanically connected end to end and positioned coaxially to each other with their piston rods extending in opposite directions, means resiliently pressing the piston rod of said first cylinder inwardly of said first cylinder, said second cylinder having its piston rod being positioned for engaging said driver, a nail guide element supported by said second cylinder which guide element will contact the object to be nailed by extension of the piston rod of said first hydraulic cylinder, means for supplying hydraulic pressure medium to said first cylinder for extending its piston rod and pushing said nail guide element against the object to be nailed, control means for causing pressure medium to be supplied to said second cylinder whose piston rod then acts upon the driver only after the nail guide element has contacted the object to nailed, and contol means for preventing said hydraulic pressure medium for leaving said first cylinder during the working movement of said second cylinder.
 2. A nailing device according to claim 1 including a spring between said holder and said first cylinder, the bias of which continously strives to retract the piston rod of said first cylinder.
 3. A nailing device according to claim 1, wherein said interconnected portions of said hydraulic cylinders consists of one end wall of each of said cylinders.
 4. A nailing device according to claim 1, comprising a control valve in said fluid pressure supply means of said hydraulic cylinders, said control valve being adapted to conduct pressure medium alternatively to one of the other of said hydraulic cylinders, means for exhausting pressure medium from said cylinders, a cut off valve in said means for exhausting adapted to keep said means for exhausting open in one position and closed in another position, a pressure dog in said pressure supplying means of said first hydraulic cylinder adapted to actuate said control valve tO supply pressure medium to said second hydraulic cylinder and block the supply to said first cylinder when a maximum pressure is achieved, and a pressure dog in said second cylinder adapted to actuate said exhaust control valve from its blocking position to its open position when the maximum pressure is required for driving the nails in is achieved. 